Implant for osteosyntheses

ABSTRACT

An implant for osteosyntheses including a plate with a plurality of holes following in succession in the longitudinal direction whereby at least most of the holes intended to receive the screws are offset in alternation generally away from a center plane whereby a center axis of each of the holes forms an acute angle with the center plane of the plate.

BACKGROUND OF THE INVENTION

This invention relates to an implant for osteosyntheses consisting of aplate provided with a plurality of holes following in succession in thelongitudinal direction and screws that can be inserted through the holesin the plate and can be screwed into a bone in the proper position,whereby at least most of the holes intended to receive the screws areoffset in alternation toward the outside, based on an imaginary centerplane of the plate, whereby the center axes of the holes form an acuteangle with the imaginary center plane of the plate and whereby the holestaper from the surface of the plate which is intended to face outward.

In the case of a known bone plate (German Utility Model 86 28 766),holes that are offset laterally with respect to the central longitudinalaxis are provided so that screws can be inserted into them. If the holesare offset by a larger angular amount of 10° to 20° (based on the roundbone cross section) from the center axis, the plate is curved about anaxis parallel to the longitudinal direction to adapt it to the bonesurface or it otherwise approximates a cylindrical shape (in particularwith a polygonal cross section). Due to the fact that the transversedimension of the bone plate need not be broadened significantly, despitethe laterally offset arrangement of the holes, considered locally, theplate can be deformed with the usual tools and adapted individually tothe shape of the bone. The width of the plate corresponds approximatelyto the width of a normal narrow plate, but the course of this plate hasa zigzag character due to the recesses. Thus, this plate may also have ahelical twist, so that the optimal fastening points can be achieved inthis case, depending on the type of fracture. Since the state-of-the-artplates are relatively broad an thus it is difficult to adapt them to therespective fracture situations, the goal is to design the known boneplate so that it can be adapted to a larger number of types of fracturesdue to the individual shaping.

In addition, a bone plate has become known (European Patent Application0 206 767) in which the holes are arranged offset laterally with respectto the central longitudinal axis, the holes being countersunkessentially in the form of a section of a sphere, and the underside ofthe head of the screws having a corresponding cross-sectional shape.Therefore, the screw head can always sit snugly in the countersunkdepression in the bone plate. However, a position between the bone plateand screw that has angular stability cannot be achieved in this way.

In the case of another known bone plate (International PatentApplication WO-97/09000), holes with a conical taper are provided andheads with a corresponding shape are also provided on the screws to beused, but no permanent connection with angular stability can be achievedwith screws running with parallel axes. In this case a large portion ofthe forces must thus be transmitted from the plate to the bone surfacethrough direct contact pressure.

In the case of the mechanical principle of conventional plateosteosynthesis used in the past, the plate is in direct contact with thebone either over the surface or with projecting strips or cams.Therefore, the contact pressure of the plate on the bone and theresulting friction of the plate against the bone is the deciding factorfor the transmission of forces from one bone fragment to the other. Thistherefore results in a direct transmission of forces from the bone tothe plate and from the plate back to the bone. As soon as a screw thathas been inserted becomes loosened, i.e., is slightly unscrewed, thisstabilization principle fails. However, there are also problems herefrom a biological standpoint. A zone of necrosis develops beneath theplate due to poor circulation. The vessels of the periosteum are clampedoff.

BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to create an implant of the typedefined preamble with which the transmission of force over a plate canbe improved significantly from both a mechanical and a biologicalstandpoint.

This is accomplished according to this invention by the fact that theholes in the plate have a conical taper and the screws have a head whichhas a conical taper toward the shaft which is provided with a thread, sothat the conical taper essentially corresponds to that of the sectionsformed by the holes, and the head can be secured in the holes in afriction-locked and/or form-fitting manner; the plate is designed withmultiple twists as seen in its longitudinal direction, whereby the mainalignment across the longitudinal extent of the plate in the area of theindividual holes runs at a right angle to the center axis of thecorresponding hole, and the plate is designed with a slight curvature,as seen from the side, whereby a tendon passed through the ends of theplate is at a distance from a center section of the plate.

These measures achieve the result that the plate is no longer in contactwith the bone under pressure. There is actually a gap between the boneand the plate. The transfer of forces from one fragment to the otherthen takes place as follows: bone—screw shaft—head of thescrew(s)—plate—head of the screw(s)—screw shaft—bone. The prerequisitefor this was the possibility created by this invention, namely thatthere would be a clamping connection between the head of the screws andthe plate having angular stability. Due to the clamping connection ofthe head of the screw in the corresponding hole in the plate at a stableangle, an optimal angular stability and protection against unscrewingare created. Such protection against unscrewing is especiallyadvantageous because unscrewing of the screws might occur merely due torepetitive alternating loads.

In addition to a secure stabilization, it is thus optionally alsopossible to use fewer screws. Circulation disorders do not occur at allbeneath the plate or they occur only to a much lesser extent, becausethe vessels of the periosteum are not clamped off.

The boreholes in the bones for inserting screws are not all aligned inone row. Therefore, splitting off of fragments is essentially prevented,and in addition, this also greatly reduces circulation disorders. Theconvergence of the screws inserted has an especially good effect. Screwsinserted successively into a bone thus approximately intersect at thecenter of the medullary space of the bone. This measure greatlyincreases the torsional stability of the plate osteosynthesis. Screwsimplanted in a line relatively close together may cause the bone tofracture when exposed to strong torsional forces. Screws implanted in aline relatively close together are also more likely to cause circulationdisorders, which have a negative effect due to the interruption in theblood vessels running in the longitudinal Haversian channels incomparison with holes arranged at an offset and thus in comparison withscrews intersecting one another sequentially.

Due to the measures according to this invention, a step toward anelastic plate has been achieved, whereby natural bone healing with thedevelopment of callous is expected, as was previously the case whenusing a plaster cast, due to the possibilities of movement.

Due to the fact that the plate is designed with multiple twists, as seenin its longitudinal direction, the main alignment across thelongitudinal extent of the plate running at least approximately at aright angle to the center axis of the corresponding hole in the area ofthe individual holes. Therefore, the plate is approximately parallel tothe surface of the bone in the respective area of attachment. Thus,there is always essentially a uniform gap between bone and plate.

It is also proposed here that the lateral limits on the plate shouldfollow essentially the offset holes and the exterior contours of theholes, so that the plate has essentially a wavy course over the lengthas seen from above. This permits an at least approximately uniformstability over the length of the plate despite the fact that the plateis manufactured by saving on material. Thus this guarantees that theplate used will not be overdimensioned.

To permit an accurate alignment especially in the transitional areabetween two bone fragments that are to be joined together, it isproposed that the two holes next to the center section of the plateshould be facing the same side limit of the plate.

In this connection, it is also advantageous if the imaginary centerplane of the plate is also the center plane of the center section of theplate. This facilitates centering of the plate on the bone.

An optimal structural design is obtained by the fact that the size ofthe cross-sectional area of the plate is at least approximately constantover its entire length. This does not result in any weak points causedby the holes in the plate.

Especially in the connecting area between two bones, i.e., in the areabridging a bone fracture, for example, special forces are to betransmitted by the plate, but it is advantageous if the cross-sectionalarea of the plate is designed to be larger in the center section than inthe other sections of the plate.

To be able to introduce the forces through the screws into each bonefragment to an equal extent, it is proposed that the distance betweenthe holes, as seen in the longitudinal direction of the plate from theends of the plate should be the same, but that the distance between thetwo holes adjacent to the center section should be greater. Due to thegreater distance of the two screws near the fracture from the fracturesurface, circulation disorders are prevented. In the bone, the mainblood vessels run in the longitudinal direction. Thus, if the screwholes near the fracture are too close to the fracture surface they mayresult in a “shadow” circulation disorder.

In addition, it is also proposed that cams projecting on one or bothsides of each hole close to the side borders should be formed on theunderside of the plate. These cams prevent the plate from being in fullsurface contact with the bone, and they may optionally increase thetorsional stability and relieve the screw necks at the transitionbetween the screw shaft and the head. These cams alone do notsignificantly interfere with circulation in the bone. The locking effectof the screws in the plate itself achieves the result that the plateultimately remains a certain distance away from the surface of the bone.

To prevent tissue damage to soft tissue, especially at the tendons whichlie above the plate or which are pulled over the plate, it is proposedthat the two ends and the edges and transitions of the plate should bedesigned to be flat and rounded.

According to another special embodiment, the center axes of the holesform an acute angle of 15° with the imaginary center plane of the plate.Due to the acute angle at which the screws are screwed in and theintersecting holes together with screws, the torsional stability of theosteosynthesis is significantly improved. The screws are under bendingstress to a much lower extent.

In addition, it is proposed according to this invention that the plateshall be manufactured from fiber-reinforced thermoplastics and theanisotropy of the elastic properties of the plate shall be adjusted tothe elasticity or rigidity of the bone. The osteosynthesis plate systemaccording to this invention is thus designed as elastic fixation. Thus,a homoelasticity is achieved, because the plate has only a similarrigidity and not an equivalent rigidity, as required of isoelasticimplants. Due to the use of such a material and the correspondingmanufacture, this yields the important advantage of a more elasticosteosynthesis. This results in less stress shielding and less reactiveosteoporosis. In addition, the development of callus is stimulated.Especially due to the combination of a plate of fiber-reinforcedthermoplastics and locking between the head of the screw and the wall ofthe hole in the plate, an elastic plate for optimal natural bone healingis achieved.

In this connection, it is especially advantageous that the anisotropy ofthe elastic properties of the plate is adjustable according to theformula: E modulus (longitudinal): E modulus (tangential)=0.3 to 0.7.The E modulus of such a homoelastic plate varies between 30 and 70 GPa(in the case of bone, this is up to 20 GPa). A ratio of approximately0.3 was obtained according to this formula for an evaluation plate. Thisratio with the evaluation plate was even lower in the case of thesystem, i.e., when mounted on a bone substitute. The offset screws bringthis ratio to a good average of approx. 0.5. Fine adjustment of theseanisotropic elastic properties can be accomplished through appropriatecontrol in the manufacturing process, e.g., in a reciprocal extrusionprocess.

Another advantageous measure is seen as the fact that the head of thescrew is provided with a thread. Preferably the head of the screw isprovided with a fine thread. This permits an optimal initial stress ofthe screw in the plate. The osteosynthesis plates used today are underinitial stress with respect to the bone. The stresses thus induced inthe bone may lead to absorption and degradation of bone and thus toweakening of the bone, which in turn increases the risk of a refractureafter removing the implant. Thanks to the initial stress of the screwsin the plate itself, no pressure burden is induced from the plate intothe bone, so this promises a greater success in healing.

Due to the use of a thread, preferably an optionally double fine thread,an optimal locking effect of the head of the screw in the correspondinghole in the plate is achieved. Due to the slightly conical head having afine thread, insertion of the screw head into the corresponding hole inthe plate is facilitated on the one hand, which could be important inthe case of a slightly eccentric bore of the screw channel in the bone,while on the other hand, this yields and effective locking of the headin the corresponding hole.

Due to the use of a thread, especially a fine thread, on the head of thescrew, good protection against loosening or ejection of the head out ofthe hole is also created. Such axial forces occur when a force acts fromthe bone against the head of the screw in the longitudinal axis of thescrew, e.g., a torsional or bending stress.

An advantageous measure is also the fact that the head of the screw isprovided with one or more longitudinal groove(s) in the area of thethread. This creates the possibility of accommodating tissue debris.

For additional locking protection of the screw, it is provided that thescrew which has been provided with a thread on its shaft shall bedesigned with an out-of-round cross section, e.g., trilobular. Afterscrewing in the screw, the bone tissue that grows back provides anatural protection, so to speak, because the out-of-round screw isclamped.

To permit the great torque to be transmitted to the best extent possiblewhen screwing in the screws, but also when unscrewing them, it isproposed that the head of the screw shall be provided with an internalpoint of action for a tool with four curved projections extendingradially outward from a central opening.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Additional features and special advantages of this invention areexplained in greater detail in the following description on the basis ofthe drawings, which show:

FIG. 1: an inclined view of a plate that can be used as an implant foran osteosynthesis;

FIG. 2 a view of a screw that can be used as an implant for anosteosynthesis;

FIG. 2A is a cross-sectional view of the shaft of FIG. 2 as taken alongthe line 2A—2A of FIG. 2 illustrating the out-of-round cross-sectionwhich may be preferably, but not necessarily, trilobular;

FIG. 3 a section through an example of use of the implant of plate andscrew on a bone;

FIG. 4 a top view of a plate;

FIG. 5 a section according to line V—V in FIG. 4;

FIG. 6 a horizontal section according to line VI—VI in FIG. 7;

FIG. 7 a side view of the plate;

FIGS. 8 through 15 sections according to lines VIII—VIII through XV—XVin FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

The implant for osteosyntheses illustrated in the drawings consists of aplate 1 provided with several holes 3 following in succession in thelongitudinal direction plus in most cases several screws 2 which can beinserted through the holes 3 in the plate 1 and can be screwed into abone 4 in the proper position. At least most of the holes 3 intended toreceive the screws 2 are arranged with an offset to the outside inalternation, based on an imaginary center plane 5 of the plate 1. Thecenter axes 6 of the holes 3 form an acute angle W with the imaginarycenter plane 5 of the plate 1. The holes 3 taper conically starting fromthe surface 7 of the plate 1 which is intended to lie on the outside.The screws 2 have a head 10 which tapers conically toward the shaft 9which is provided with a thread 8, essentially corresponding to thesections formed by the holes 3. The screw 2 can be secured in the holes3 by its head 10 in a friction-locked and/or form-fitting manner.

The side borders 11, 12 of the plate 1 follow essentially the offsetholes 3 and also the outside contours of the holes 3. The plate 1therefore has an essentially wavy course over its length as seen in atop view. Furthermore, the plate 1 is designed with multiple twists, asseen in its longitudinal direction, with the main alignment across thelongitudinal extent of the plate running at least approximately at aright angle to the center axis 6 of the corresponding hole 3 in the areaof the individual holes 3.

The two holes 3 closest to the center section 13 of the plate, based ontheir length, are facing the same side borders 11 (or 12) of the plate1. This center section 13 need not always be arranged exactly in thecenter, based on the length of the plate 1. In the case of plates havingan even number of holes 3, it will probably always be the center (exceptin the case of extremely long plates). When there is an uneven number ofholes 3, the center section 13 is between the holes x/2+0.5 and x/2−0.5.The construction here is advantageously such that the imaginary centerplane 5 of the plate 1 is also the center plane 5 of the center section13 of the plate 1.

When seen from the side, the plate 1 is designed with a slightcurvature, whereby the distance of a tendon passing through the ends 14of the plate to the center section 13 may amount to approximately 2 mm,for example. This longitudinal bending can also counteract the bowing ofa fracture when a bending moment acts perpendicularly on the undersideof the plate. Due to this longitudinal bending, a better adaptation tothe geometry of the bone of the forearm has become made possible.

The size of the cross-sectional area of the plate 1 is at leastapproximately constant over its entire length. However, thecross-sectional area of the plate 1 in the area of the center section 13may be designed to be larger than in the other sections of the plate 1.Thus, an additional optimization of the torsional stability is possibleprecisely in this center section which extends over the fracture area.

The distance between the holes 3 as seen in the longitudinal directionof the plate 1, starting from the ends 14 of the plate is uniform.However, the distance between the two holes 3 adjacent to the centersection 13 may be greater. Depending on the area of use or specialcircumstances, it is also conceivable to design the hole spacings to bevariable.

On the underside 16 of the plate 1, cams 17 which project outward on oneor both sides of each hole 3 may be provided close to the side borders11, 12. These cams 17 may be advantageous in installing the plate, tothereby produce a suitable gap between the surface of the bone and theplate 1. In the final state, however, the plate 1 is not pressed againstthe surface of the bone 4, so that the cams rest on the surface withoutany pressure and practically only secure the distance in installationthemselves. Due to screwing in the screws themselves, there is by nomeans any pressure of the plate against the surface of the bone.

The two ends 14 of the plate 1, as well as all edges and transitions,are designed to be flat and rounded. The shoulders 15 which fare shownas approximately cylindrical in the figure are sections that areattached only for manufacturing reasons, but as a rule they are removedbefore the final implantation.

To achieve an optimal convergence of the screws 2 which are to bescrewed in (see also the diagram in FIG. 3), the center axes 6 of theholes 3 are aligned in an acute angle W to the imaginary center plane 5of the plate 1, and thus when the screws 2 are screwed in, their centeraxes are also so aligned. The center axes 6 of the holes 3 form an acuteangle W of approximately 15° with the imaginary center plane 5 of theplate 1 to advantage.

The plate 1 and the screw 2 as well are made of fiber-reinforcedthermoplastics to advantage. They may be manufactured in a moldingprocess, such as an extrusion process or in a reciprocal extrusionprocess. The anisotropy of the elastic properties of the plate 1 isadjustable to the elasticity or rigidity of the bone 4. In manufactureof the plate, the anisotropy of the elastic properties is adjustableaccording to the formula: E modulus (longitudinal): E modulus(tangential)=0.3 to 0.7. An average of 0.5 is regarded as optimal.

In order to achieve a proper locking effect of the head 10 of the screw2 in the corresponding hole 3 in the plate 1, i.e., to achieve therequired rigidity of this connection, the head 10 of the screw 2 isadvantageously provided with a thread 18. A fine thread is provided inan optimal manner on the head 10 of the screw which is designed with aconical taper in a corresponding construction with the hole 3. In thecase of a dual-thread embodiment of the fine thread, a thread pitchwhich is adapted to the thread 8 on the shaft 9 is achieved, and inaddition, a fixed locking effect of the head 10 of the screw 2 withrespect to the plate 1 is also obtained. If in addition the head 10 ofthe screw 2 is also provided with one or more longitudinal groove(s) 20in the area of the thread 18, this creates a possibility foraccommodating tissue debris. When the screw 2 is screwed in, suddenly anincrease in torque is achieved in the last couple of revolutions,whereby this higher torque comes about due to the mutual engagement ofthe wall of the hole 3 and the head 10 of the screw 2. This means anoptimal locking effect between the screw 2 and the plate 1, so there cannever be any stripping of the thread 8 in the bone 4.

To achieve another possibility of locking the screw, the screw 2 isdesigned with an out-of-round cross section, e.g., trilobular, on itsshaft 9 which is provided with a thread 8. Such cross-sectional shapesare usually referred to as being “orbiform.” Within the scope of thisinvention, it would also be conceivable to design the area of the head10 of the screw 2 with an out-of-round cross section.

The head 10 of the screw 2 is provided with an internal tool actionpoint 19, which is advantageous for installing and also removing suchscrews. An advantageous embodiment would provide for an internal toolacting point 19 with four curved projections extending radially outwardfrom a central opening. In this way, a very advantageous transfer oftorque is possible.

The sectional diagrams in FIGS. 8 through 15 do not require any furtherexplanation. The technical details are already apparent from thepreceding description, and the sectional diagram speaks for itself.

Essential inventive features are embodied in both the plate 1 and in thescrew 2, additionally entailing ion their totality an optimal increasein the suitability of implants.

What is claimed is:
 1. An implant for osteosyntheses, comprising: aplate (1) provided with a surface defining a plurality of holes (3) andtwo ends, the plate defining a longitudinal direction and a center planedisposed generally parallel to the longitudinal direction and locatedgenerally perpendicular to the surface, the holes generally followingone another in the longitudinal direction and being positioned outwardlyoffset from the center plane with at least most of the holes beingoffset outwardly from the center plane in a direction generally oppositefrom neighboring holes, the holes each having a center axis (6) formingan acute angle (W) with the center plane (5) of the plate (1) such that,when inserted, the screws are not all aligned in parallel, each of theholes (3) generally tapering inwardly from the surface (7) to form aconical taper; the screws (2) each having a head (10) which tapers in aconical shape toward a shaft (9) and adapted to be secured in the holes(3) in a friction-locked and/or form-fitting manner; the plate (1) beingconfigured to have multiple twists as seen in its longitudinaldirection, whereby in the area of the individual holes (3) the mainalignment across the longitudinal extent of the plate (1) runs at aright angle to the center axis (6) of the corresponding hole (3) and theplate (1) has a slight curvature along the longitudinal direction,whereby a tendon placed through the two ends (14) of the plate (1) is ata distance from a center section (13) of the plate (1).
 2. The implantaccording to claim 1, wherein the plate (1) further comprises a lengthand two side borders (11, 12) generally follow an outside contour of theso that the plate (1) has an essentially wavy course over the length, asviewed along the center plane.
 3. The implant according to claim 1,wherein the center plane (5) of the plate (1) is centrally aligned withthe center section (13) of the plate (1).
 4. The implant according toclaim 1, wherein a cross-sectional area of the plate (1), not includingthe area occupied by the holes, as taken generally perpendicularly tothe longitudinal axis, is approximately constant over an entire lengthof the plate.
 5. The implant according to claim 1, wherein thecross-sectional area of the plate (1), as measured generallyperpendicularly to the longitudinal axis, is designed to be greater inthe area of the center section (13) than in the other sections of theplate (1).
 6. The implant according to claim 1, wherein a cam (17)projecting outward on one or both sides of each hole (3) is providednear two side borders (11, 12) on an underside (16) of the plate (1). 7.The implant according to claim 1, wherein the two ends (14) and aplurality of edges and transitions of the plate (1) are designed to beflat and rounded.
 8. The implant according to claim 1, wherein the head(10) of the screw (2) is provided with an internal tool engagement point(19) with four curved projections extending radically outward from acentral opening.
 9. The implant according to claim 1, wherein two of theholes (3) closest to the center section (13) of the plate (1) are offsetfrom the center plane in the same direction.
 10. The implant accordingto claim 9, wherein a distance between the holes (3) in the longitudinaldirection of the plate (1), as seen along the center plane, is the sameexcept for the two holes (3) adjacent to the center section (13) whichare further spaced apart.
 11. The implant according to claim 1, whereinthe head (10) of the screw (2) is provided with a thread (18).
 12. Theimplant according to claim 11, wherein the head (10) of the screw (2) isprovided with one or more longitudinal groove(s) proximate to the thread(18).
 13. An implant for osteosyntheses, comprising: a plate providedwith a surface defining a plurality of holes, the plate defining alongitudinal direction and a center plane disposed generally parallel tothe longitudinal direction and located generally perpendicular to tilesurface, the plurality of holes generally following one another in thelongitudinal direction and being positioned outwardly offset from thecenter plane with at least most of the plurality of holes being offsetoutwardly from the center plane in a direction generally opposite fromneighboring holes, the plurality of holes each having a center axisforming an acute angle (W) with the center plane of the plate.
 14. Theimplant of claim 13, wherein the plate has a slight curvature, as viewedfrom a side, whereby a tendon placed through an end of the plate isspaced from a center section of the plate.
 15. The implant of claim 13,wherein a cross-sectional area of the plate, not including the areaoccupied by the holes, as taken generally perpendicularly to thelongitudinal axis, is generally constant throughout the plate.
 16. Theimplant of claim 13, wherein the center axis of each of the plurality ofholes forms an acute angle of approximately fifteen (15°) degrees withthe center plane of the plate.
 17. The implant of claim 13, wherein theplate is manufactured from fiber-reinforced thermoplastics, and theanisotropy of the elastic properties of the plate is adjusted to theelasticity or rigidity of the bone.
 18. The implant of claim 13, whereinthe plurality of screws tend to converge when engaged with the plate dueto the acute angle between the center as of each of the plurality ofholes and the center plane.
 19. The implant according to claim 13,wherein the out-of-round cross section is trilobular.
 20. An implant forosteosyntheses, comprising: a plate (1) provided with a surface defininga plurality of holes (3) and two ends, the plate defining a longitudinaldirection and a center plane disposed generally parallel to thelongitudinal direction and located generally perpendicular to thesurface, the holes generally following one another in the longitudinaldirection and being positioned outwardly offset from the center planewith at least most of the holes being offset outwardly from the centerplane in a direction generally opposite from neighboring holes, theholes each having a center axis (6) forming an acute angle (W) with thecenter plane (5) of the plate (1) such that, when inserted, the screwsare not all aligned in parallel, the holes (3) each generally taperinginwardly from the surface (7) to form a conical taper; the screws (2)each having a head (10) which tapers in a conical shape toward a shaft(9) and adapted to be secured in the holes (3) in a friction-lockedand/or form-fitting manner; the plate (1) being configured to havemultiple twists as seen in its longitudinal direction, whereby in thearea of the individual holes (3) the main alignment across thelongitudinal extent of the plate (1) runs at a right angle to the centeraxis (6) of the corresponding hole (3) and the plate (1) has a slightcurvature along the longitudinal direction, whereby a tendon placedthrough the two ends (14) of the plate (1) is at a distance from acenter section (13) of the plate (1), wherein the center axis (6) ofeach of the holes (3) forms an acute angle (W) of approximately fifteen(15°) degrees with the center plane (5) of the plate (1).
 21. An implantfor osteosyntheses, comprising: a plate (1) provided with a surfacedefining a plurality of holes (3) and two ends, the plate defines alongitudinal direction and a center plane disposed generally parallel tothe longitudinal direction and located generally perpendicular to thesurface, the holes generally following one another in the longitudinaldirection and being positioned outwardly offset from the center planewith at least most of the holes being offset outwardly from the centerplane in a direction generally opposite from neighboring holes, theholes each having a center axis (6) forming an acute angle (W) with thecenter plane (5) of the plate (1) such that, when inserted, the screwsare not all aligned in parallel, the holes (3) each generally taperinginwardly from the surface (7) to form a conical taper; the screws (2)each having a head (10) which tapers in a conical shape toward a shaft(9) and adapted to be secured in the holes (3) in a friction-lockedand/or form-fitting manner; the plate (1) being configured to havemultiple twists as seen in its longitudinal direction, whereby in thearea of the individual holes (3) the main alignment across thelongitudinal extent of the plate (1) runs at a right angle to the centeraxis (6) of the corresponding hole (3) and the plate (1) has a slightcurvature along the longitudinal direction, whereby a tendon placedthrough the two ends (14) of the plate (1) is at a distance from acenter section (13) of the plate (1), wherein the plate (1) ismanufactured from fiber-reinforced thermoplastics, and the anisotropy ofthe elastic properties of the plate (1) is adjusted to the elasticity orrigidity of the bone (4).
 22. An implant for osteosyntheses, comprising:a plate (1) provided with a surface defining a plurality of holes (3)and two ends, the plate defines a longitudinal direction and a centerplane disposed generally parallel to the longitudinal direction andlocated generally perpendicular to the surface, the holes generallyfollowing one another in the longitudinal direction and are positionedoutwardly offset from the center plane with at least most of the holesbeing offset outwardly from the center plane in a direction generallyopposite from neighboring holes, the holes each having a center axis (6)forming an acute angle (W) with the center plane (5) of the plate (1)such that, when inserted, the screws being not all aligned in parallel,each of the holes (3) generally tapering inwardly from the surface (7)to form a conical taper; the screws (2) each having a head (10) whichtapers in a conical shape toward a shaft (9) and adapted to be securedin the holes (3) in a friction-locked and/or form-fitting manner; theplate (1) being configured to have multiple twists as seen in itslongitudinal direction, whereby in the area of the individual holes (3)the main alignment across the longitudinal extent of the plate (1) runsat a right angle to the center axis (6) of the corresponding hole (3)and the plate (1) has a slight curvature along the longitudinaldirection, whereby a tendon placed through the two ends (14) of theplate (1) is at a distance from a center section (13) of the plate (1),wherein the anisotropy of the elastic properties of the plate (1) isadjustable according to the formula: E modulus (longitudinal): E modulus(tangential)=0.3 to 0.7.
 23. An implant for osteosyntheses, comprising:a plate (1) provided with a surface defining a plurality of holes (3)and two ends, the plate defines a longitudinal direction and a centerplane disposed generally parallel to the longitudinal direction andlocated generally perpendicular to the surface, the holes generallyfollowing one another in the longitudinal direction and are positionedoutwardly offset from the center plane with at least most of the holesbeing offset outwardly from the center plane in a direction generallyopposite from neighboring holes, the holes each having a center axis (6)forming an acute angle (W) with the center plane (5) of the plate (1)such that, when inserted, the screws are not all aligned in parallel,the holes (3) each generally taper inwardly from the surface (7) to forma conical taper; the screws (2) each have a head (10) which tapers in aconical shape toward a shaft (9) and can be secured in the holes (3) ina friction-locked and/or form-fitting manner; the plate (1) beingconfigured to have multiple twists as seen in its longitudinaldirection, whereby in the area of the individual holes (3) the mainalignment across the longitudinal extent of the plate (1) runs at aright angle to the center axis (6) of the corresponding hole (3) and theplate (1) has a slight curvature along the longitudinal direction,whereby a tendon placed through the two ends (14) of the plate (1) is ata distance from a center section (13) of the plate (1), wherein theshaft (9) of the screw (2) has an out-of-round cross section, as takengenerally perpendicularly to a longitudinal axis of the shaft (9), atleast one thread (8) being located generally around the shaft.